Farooqui Ausaf A, Manly Tom
MRC-Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge, CB2 7EF, UK.
Psychol Res. 2019 Feb;83(1):84-103. doi: 10.1007/s00426-018-1051-2. Epub 2018 Jul 18.
We select and execute extended task episodes ('make tea') as one entity and not individually execute their very many components (find kettle, boil water, etc.). Such hierarchical execution is thought to occur in familiar task situations with pre-existing task episode-related scripts that once selected, control the identity and sequence of component steps. Here, in contrast, we show hierarchical execution of extended behavior in situations, where the identity and sequence of component steps were unknown and a predetermined script could not have existed. Participants performed a rule-switching task in which the rule to be applied on each trial could not be predicted. Crucially, they were biased into construing a recurring instance of three or five trials as a single task episode. Behavioral signs of hierarchical execution, identical to those seen during memorized task-sequence executions, were present. These included longer reaction time on the first trial of each episode that was proportionate to the length of that episode, and absence of rule switch costs only between those consecutive trials that crossed episode boundaries. Hierarchical execution thus occurs every time the to-be-executed behavior is construed as one task episode, and is not limited to predictable sequences. We suggest that hierarchical execution occurs because task episodes are controlled and executed through goal-related entities assembled at the beginning of execution that subsume the execution and instantiate purposive control across time until the goal is complete.
我们将扩展任务情节（“泡茶”）作为一个整体来选择和执行，而不是单独执行其众多组成部分（找到水壶、烧水等）。这种分层执行被认为发生在熟悉的任务情境中，这些情境具有预先存在的与任务情节相关的脚本，一旦被选中，就会控制组成步骤的识别和顺序。相比之下，在这里我们展示了在组成步骤的识别和顺序未知且不可能存在预定脚本的情况下扩展行为的分层执行。参与者执行了一项规则切换任务，其中每次试验要应用的规则是无法预测的。关键的是，他们倾向于将三到五次试验的重复实例解释为一个单一的任务情节。出现了与记忆任务序列执行期间所见相同的分层执行行为迹象。这些迹象包括每个情节的第一次试验中较长的反应时间，该时间与该情节的长度成比例，并且仅在跨越情节边界的那些连续试验之间不存在规则切换成本。因此，每当待执行的行为被解释为一个任务情节时就会发生分层执行，并且不限于可预测的序列。我们认为发生分层执行是因为任务情节是通过在执行开始时组装的与目标相关的实体来控制和执行的，这些实体包含执行并在目标完成之前跨时间实例化目的控制。
